prefect_gcp.bigquery

Tasks for interacting with GCP BigQuery

BigQueryWarehouse

Bases: DatabaseBlock

A block for querying a database with BigQuery.

Upon instantiating, a connection to BigQuery is established and maintained for the life of the object until the close method is called.

It is recommended to use this block as a context manager, which will automatically close the connection and its cursors when the context is exited.

It is also recommended that this block is loaded and consumed within a single task or flow because if the block is passed across separate tasks and flows, the state of the block's connection and cursor could be lost.

Attributes:

Name	Type	Description
gcp_credentials	GcpCredentials	The credentials to use to authenticate.
fetch_size	int	The number of rows to fetch at a time when calling fetch_many. Note, this parameter is executed on the client side and is not passed to the database. To limit on the server side, add the LIMIT clause, or the dialect's equivalent clause, like TOP, to the query.

Source code in prefect_gcp/bigquery.py

class BigQueryWarehouse(DatabaseBlock):
    """
    A block for querying a database with BigQuery.

    Upon instantiating, a connection to BigQuery is established
    and maintained for the life of the object until the close method is called.

    It is recommended to use this block as a context manager, which will automatically
    close the connection and its cursors when the context is exited.

    It is also recommended that this block is loaded and consumed within a single task
    or flow because if the block is passed across separate tasks and flows,
    the state of the block's connection and cursor could be lost.

    Attributes:
        gcp_credentials: The credentials to use to authenticate.
        fetch_size: The number of rows to fetch at a time when calling fetch_many.
            Note, this parameter is executed on the client side and is not
            passed to the database. To limit on the server side, add the `LIMIT`
            clause, or the dialect's equivalent clause, like `TOP`, to the query.
    """  # noqa

    _block_type_name = "BigQuery Warehouse"
    _logo_url = "https://cdn.sanity.io/images/3ugk85nk/production/10424e311932e31c477ac2b9ef3d53cefbaad708-250x250.png"  # noqa
    _documentation_url = "https://prefecthq.github.io/prefect-gcp/bigquery/#prefect_gcp.bigquery.BigQueryWarehouse"  # noqa: E501

    gcp_credentials: GcpCredentials
    fetch_size: int = Field(
        default=1, description="The number of rows to fetch at a time."
    )

    _connection: Optional["Connection"] = None
    _unique_cursors: Dict[str, "Cursor"] = None

    def _start_connection(self):
        """
        Starts a connection.
        """
        with self.gcp_credentials.get_bigquery_client() as client:
            self._connection = Connection(client=client)

    def block_initialization(self) -> None:
        super().block_initialization()
        if self._connection is None:
            self._start_connection()

        if self._unique_cursors is None:
            self._unique_cursors = {}

    def get_connection(self) -> "Connection":
        """
        Get the opened connection to BigQuery.
        """
        return self._connection

    def _get_cursor(self, inputs: Dict[str, Any]) -> Tuple[bool, "Cursor"]:
        """
        Get a BigQuery cursor.

        Args:
            inputs: The inputs to generate a unique hash, used to decide
                whether a new cursor should be used.

        Returns:
            Whether a cursor is new and a BigQuery cursor.
        """
        input_hash = hash_objects(inputs)
        assert input_hash is not None, (
            "We were not able to hash your inputs, "
            "which resulted in an unexpected data return; "
            "please open an issue with a reproducible example."
        )
        if input_hash not in self._unique_cursors.keys():
            new_cursor = self._connection.cursor()
            self._unique_cursors[input_hash] = new_cursor
            return True, new_cursor
        else:
            existing_cursor = self._unique_cursors[input_hash]
            return False, existing_cursor

    def reset_cursors(self) -> None:
        """
        Tries to close all opened cursors.
        """
        input_hashes = tuple(self._unique_cursors.keys())
        for input_hash in input_hashes:
            cursor = self._unique_cursors.pop(input_hash)
            try:
                cursor.close()
            except Exception as exc:
                self.logger.warning(
                    f"Failed to close cursor for input hash {input_hash!r}: {exc}"
                )

    @sync_compatible
    async def fetch_one(
        self,
        operation: str,
        parameters: Optional[Dict[str, Any]] = None,
        **execution_options: Dict[str, Any],
    ) -> "Row":
        """
        Fetch a single result from the database.

        Repeated calls using the same inputs to *any* of the fetch methods of this
        block will skip executing the operation again, and instead,
        return the next set of results from the previous execution,
        until the reset_cursors method is called.

        Args:
            operation: The SQL query or other operation to be executed.
            parameters: The parameters for the operation.
            **execution_options: Additional options to pass to `connection.execute`.

        Returns:
            A tuple containing the data returned by the database,
                where each row is a tuple and each column is a value in the tuple.

        Examples:
            Execute operation with parameters, fetching one new row at a time:
            ```python
            from prefect_gcp.bigquery import BigQueryWarehouse

            with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
                operation = '''
                    SELECT word, word_count
                    FROM `bigquery-public-data.samples.shakespeare`
                    WHERE corpus = %(corpus)s
                    AND word_count >= %(min_word_count)s
                    ORDER BY word_count DESC
                    LIMIT 3;
                '''
                parameters = {
                    "corpus": "romeoandjuliet",
                    "min_word_count": 250,
                }
                for _ in range(0, 3):
                    result = warehouse.fetch_one(operation, parameters=parameters)
                    print(result)
            ```
        """
        inputs = dict(
            operation=operation,
            parameters=parameters,
            **execution_options,
        )
        new, cursor = self._get_cursor(inputs)
        if new:
            await run_sync_in_worker_thread(cursor.execute, **inputs)

        result = await run_sync_in_worker_thread(cursor.fetchone)
        return result

    @sync_compatible
    async def fetch_many(
        self,
        operation: str,
        parameters: Optional[Dict[str, Any]] = None,
        size: Optional[int] = None,
        **execution_options: Dict[str, Any],
    ) -> List["Row"]:
        """
        Fetch a limited number of results from the database.

        Repeated calls using the same inputs to *any* of the fetch methods of this
        block will skip executing the operation again, and instead,
        return the next set of results from the previous execution,
        until the reset_cursors method is called.

        Args:
            operation: The SQL query or other operation to be executed.
            parameters: The parameters for the operation.
            size: The number of results to return; if None or 0, uses the value of
                `fetch_size` configured on the block.
            **execution_options: Additional options to pass to `connection.execute`.

        Returns:
            A list of tuples containing the data returned by the database,
                where each row is a tuple and each column is a value in the tuple.

        Examples:
            Execute operation with parameters, fetching two new rows at a time:
            ```python
            from prefect_gcp.bigquery import BigQueryWarehouse

            with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
                operation = '''
                    SELECT word, word_count
                    FROM `bigquery-public-data.samples.shakespeare`
                    WHERE corpus = %(corpus)s
                    AND word_count >= %(min_word_count)s
                    ORDER BY word_count DESC
                    LIMIT 6;
                '''
                parameters = {
                    "corpus": "romeoandjuliet",
                    "min_word_count": 250,
                }
                for _ in range(0, 3):
                    result = warehouse.fetch_many(
                        operation,
                        parameters=parameters,
                        size=2
                    )
                    print(result)
            ```
        """
        inputs = dict(
            operation=operation,
            parameters=parameters,
            **execution_options,
        )
        new, cursor = self._get_cursor(inputs)
        if new:
            await run_sync_in_worker_thread(cursor.execute, **inputs)

        size = size or self.fetch_size
        result = await run_sync_in_worker_thread(cursor.fetchmany, size=size)
        return result

    @sync_compatible
    async def fetch_all(
        self,
        operation: str,
        parameters: Optional[Dict[str, Any]] = None,
        **execution_options: Dict[str, Any],
    ) -> List["Row"]:
        """
        Fetch all results from the database.

        Repeated calls using the same inputs to *any* of the fetch methods of this
        block will skip executing the operation again, and instead,
        return the next set of results from the previous execution,
        until the reset_cursors method is called.

        Args:
            operation: The SQL query or other operation to be executed.
            parameters: The parameters for the operation.
            **execution_options: Additional options to pass to `connection.execute`.

        Returns:
            A list of tuples containing the data returned by the database,
                where each row is a tuple and each column is a value in the tuple.

        Examples:
            Execute operation with parameters, fetching all rows:
            ```python
            from prefect_gcp.bigquery import BigQueryWarehouse

            with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
                operation = '''
                    SELECT word, word_count
                    FROM `bigquery-public-data.samples.shakespeare`
                    WHERE corpus = %(corpus)s
                    AND word_count >= %(min_word_count)s
                    ORDER BY word_count DESC
                    LIMIT 3;
                '''
                parameters = {
                    "corpus": "romeoandjuliet",
                    "min_word_count": 250,
                }
                result = warehouse.fetch_all(operation, parameters=parameters)
            ```
        """
        inputs = dict(
            operation=operation,
            parameters=parameters,
            **execution_options,
        )
        new, cursor = self._get_cursor(inputs)
        if new:
            await run_sync_in_worker_thread(cursor.execute, **inputs)

        result = await run_sync_in_worker_thread(cursor.fetchall)
        return result

    @sync_compatible
    async def execute(
        self,
        operation: str,
        parameters: Optional[Dict[str, Any]] = None,
        **execution_options: Dict[str, Any],
    ) -> None:
        """
        Executes an operation on the database. This method is intended to be used
        for operations that do not return data, such as INSERT, UPDATE, or DELETE.

        Unlike the fetch methods, this method will always execute the operation
        upon calling.

        Args:
            operation: The SQL query or other operation to be executed.
            parameters: The parameters for the operation.
            **execution_options: Additional options to pass to `connection.execute`.

        Examples:
            Execute operation with parameters:
            ```python
            from prefect_gcp.bigquery import BigQueryWarehouse

            with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
                operation = '''
                    CREATE TABLE mydataset.trips AS (
                    SELECT
                        bikeid,
                        start_time,
                        duration_minutes
                    FROM
                        bigquery-public-data.austin_bikeshare.bikeshare_trips
                    LIMIT %(limit)s
                    );
                '''
                warehouse.execute(operation, parameters={"limit": 5})
            ```
        """
        inputs = dict(
            operation=operation,
            parameters=parameters,
            **execution_options,
        )
        cursor = self._get_cursor(inputs)[1]
        await run_sync_in_worker_thread(cursor.execute, **inputs)

    @sync_compatible
    async def execute_many(
        self,
        operation: str,
        seq_of_parameters: List[Dict[str, Any]],
    ) -> None:
        """
        Executes many operations on the database. This method is intended to be used
        for operations that do not return data, such as INSERT, UPDATE, or DELETE.

        Unlike the fetch methods, this method will always execute the operations
        upon calling.

        Args:
            operation: The SQL query or other operation to be executed.
            seq_of_parameters: The sequence of parameters for the operation.

        Examples:
            Create mytable in mydataset and insert two rows into it:
            ```python
            from prefect_gcp.bigquery import BigQueryWarehouse

            with BigQueryWarehouse.load("bigquery") as warehouse:
                create_operation = '''
                CREATE TABLE IF NOT EXISTS mydataset.mytable (
                    col1 STRING,
                    col2 INTEGER,
                    col3 BOOLEAN
                )
                '''
                warehouse.execute(create_operation)
                insert_operation = '''
                INSERT INTO mydataset.mytable (col1, col2, col3) VALUES (%s, %s, %s)
                '''
                seq_of_parameters = [
                    ("a", 1, True),
                    ("b", 2, False),
                ]
                warehouse.execute_many(
                    insert_operation,
                    seq_of_parameters=seq_of_parameters
                )
            ```
        """
        inputs = dict(
            operation=operation,
            seq_of_parameters=seq_of_parameters,
        )
        cursor = self._get_cursor(inputs)[1]
        await run_sync_in_worker_thread(cursor.executemany, **inputs)

    def close(self):
        """
        Closes connection and its cursors.
        """
        try:
            self.reset_cursors()
        finally:
            if self._connection is not None:
                self._connection.close()
                self._connection = None

    def __enter__(self):
        """
        Start a connection upon entry.
        """
        return self

    def __exit__(self, *args):
        """
        Closes connection and its cursors upon exit.
        """
        self.close()

    def __getstate__(self):
        """ """
        data = self.__dict__.copy()
        data.update({k: None for k in {"_connection", "_unique_cursors"}})
        return data

    def __setstate__(self, data: dict):
        """ """
        self.__dict__.update(data)
        self._unique_cursors = {}
        self._start_connection()

close

Closes connection and its cursors.

Source code in prefect_gcp/bigquery.py

def close(self):
    """
    Closes connection and its cursors.
    """
    try:
        self.reset_cursors()
    finally:
        if self._connection is not None:
            self._connection.close()
            self._connection = None

execute async

Executes an operation on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE.

Unlike the fetch methods, this method will always execute the operation upon calling.

Parameters:

Name	Type	Description	Default
operation	str	The SQL query or other operation to be executed.	required
parameters	Optional[Dict[str, Any]]	The parameters for the operation.	None
**execution_options	Dict[str, Any]	Additional options to pass to connection.execute.	{}

Examples:

Execute operation with parameters:

from prefect_gcp.bigquery import BigQueryWarehouse

with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
    operation = '''
        CREATE TABLE mydataset.trips AS (
        SELECT
            bikeid,
            start_time,
            duration_minutes
        FROM
            bigquery-public-data.austin_bikeshare.bikeshare_trips
        LIMIT %(limit)s
        );
    '''
    warehouse.execute(operation, parameters={"limit": 5})

Source code in prefect_gcp/bigquery.py

@sync_compatible
async def execute(
    self,
    operation: str,
    parameters: Optional[Dict[str, Any]] = None,
    **execution_options: Dict[str, Any],
) -> None:
    """
    Executes an operation on the database. This method is intended to be used
    for operations that do not return data, such as INSERT, UPDATE, or DELETE.

    Unlike the fetch methods, this method will always execute the operation
    upon calling.

    Args:
        operation: The SQL query or other operation to be executed.
        parameters: The parameters for the operation.
        **execution_options: Additional options to pass to `connection.execute`.

    Examples:
        Execute operation with parameters:
        ```python
        from prefect_gcp.bigquery import BigQueryWarehouse

        with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
            operation = '''
                CREATE TABLE mydataset.trips AS (
                SELECT
                    bikeid,
                    start_time,
                    duration_minutes
                FROM
                    bigquery-public-data.austin_bikeshare.bikeshare_trips
                LIMIT %(limit)s
                );
            '''
            warehouse.execute(operation, parameters={"limit": 5})
        ```
    """
    inputs = dict(
        operation=operation,
        parameters=parameters,
        **execution_options,
    )
    cursor = self._get_cursor(inputs)[1]
    await run_sync_in_worker_thread(cursor.execute, **inputs)

execute_many async

Executes many operations on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE.

Unlike the fetch methods, this method will always execute the operations upon calling.

Parameters:

Name	Type	Description	Default
operation	str	The SQL query or other operation to be executed.	required
seq_of_parameters	List[Dict[str, Any]]	The sequence of parameters for the operation.	required

Examples:

Create mytable in mydataset and insert two rows into it:

from prefect_gcp.bigquery import BigQueryWarehouse

with BigQueryWarehouse.load("bigquery") as warehouse:
    create_operation = '''
    CREATE TABLE IF NOT EXISTS mydataset.mytable (
        col1 STRING,
        col2 INTEGER,
        col3 BOOLEAN
    )
    '''
    warehouse.execute(create_operation)
    insert_operation = '''
    INSERT INTO mydataset.mytable (col1, col2, col3) VALUES (%s, %s, %s)
    '''
    seq_of_parameters = [
        ("a", 1, True),
        ("b", 2, False),
    ]
    warehouse.execute_many(
        insert_operation,
        seq_of_parameters=seq_of_parameters
    )

Source code in prefect_gcp/bigquery.py

@sync_compatible
async def execute_many(
    self,
    operation: str,
    seq_of_parameters: List[Dict[str, Any]],
) -> None:
    """
    Executes many operations on the database. This method is intended to be used
    for operations that do not return data, such as INSERT, UPDATE, or DELETE.

    Unlike the fetch methods, this method will always execute the operations
    upon calling.

    Args:
        operation: The SQL query or other operation to be executed.
        seq_of_parameters: The sequence of parameters for the operation.

    Examples:
        Create mytable in mydataset and insert two rows into it:
        ```python
        from prefect_gcp.bigquery import BigQueryWarehouse

        with BigQueryWarehouse.load("bigquery") as warehouse:
            create_operation = '''
            CREATE TABLE IF NOT EXISTS mydataset.mytable (
                col1 STRING,
                col2 INTEGER,
                col3 BOOLEAN
            )
            '''
            warehouse.execute(create_operation)
            insert_operation = '''
            INSERT INTO mydataset.mytable (col1, col2, col3) VALUES (%s, %s, %s)
            '''
            seq_of_parameters = [
                ("a", 1, True),
                ("b", 2, False),
            ]
            warehouse.execute_many(
                insert_operation,
                seq_of_parameters=seq_of_parameters
            )
        ```
    """
    inputs = dict(
        operation=operation,
        seq_of_parameters=seq_of_parameters,
    )
    cursor = self._get_cursor(inputs)[1]
    await run_sync_in_worker_thread(cursor.executemany, **inputs)

fetch_all async

Fetch all results from the database.

Repeated calls using the same inputs to any of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called.

Parameters:

Name	Type	Description	Default
operation	str	The SQL query or other operation to be executed.	required
parameters	Optional[Dict[str, Any]]	The parameters for the operation.	None
**execution_options	Dict[str, Any]	Additional options to pass to connection.execute.	{}

Returns:

Type	Description
List[Row]	A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple.

Examples:

Execute operation with parameters, fetching all rows:

from prefect_gcp.bigquery import BigQueryWarehouse

with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
    operation = '''
        SELECT word, word_count
        FROM `bigquery-public-data.samples.shakespeare`
        WHERE corpus = %(corpus)s
        AND word_count >= %(min_word_count)s
        ORDER BY word_count DESC
        LIMIT 3;
    '''
    parameters = {
        "corpus": "romeoandjuliet",
        "min_word_count": 250,
    }
    result = warehouse.fetch_all(operation, parameters=parameters)

Source code in prefect_gcp/bigquery.py

@sync_compatible
async def fetch_all(
    self,
    operation: str,
    parameters: Optional[Dict[str, Any]] = None,
    **execution_options: Dict[str, Any],
) -> List["Row"]:
    """
    Fetch all results from the database.

    Repeated calls using the same inputs to *any* of the fetch methods of this
    block will skip executing the operation again, and instead,
    return the next set of results from the previous execution,
    until the reset_cursors method is called.

    Args:
        operation: The SQL query or other operation to be executed.
        parameters: The parameters for the operation.
        **execution_options: Additional options to pass to `connection.execute`.

    Returns:
        A list of tuples containing the data returned by the database,
            where each row is a tuple and each column is a value in the tuple.

    Examples:
        Execute operation with parameters, fetching all rows:
        ```python
        from prefect_gcp.bigquery import BigQueryWarehouse

        with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
            operation = '''
                SELECT word, word_count
                FROM `bigquery-public-data.samples.shakespeare`
                WHERE corpus = %(corpus)s
                AND word_count >= %(min_word_count)s
                ORDER BY word_count DESC
                LIMIT 3;
            '''
            parameters = {
                "corpus": "romeoandjuliet",
                "min_word_count": 250,
            }
            result = warehouse.fetch_all(operation, parameters=parameters)
        ```
    """
    inputs = dict(
        operation=operation,
        parameters=parameters,
        **execution_options,
    )
    new, cursor = self._get_cursor(inputs)
    if new:
        await run_sync_in_worker_thread(cursor.execute, **inputs)

    result = await run_sync_in_worker_thread(cursor.fetchall)
    return result

fetch_many async

Fetch a limited number of results from the database.

Repeated calls using the same inputs to any of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called.

Parameters:

Name	Type	Description	Default
operation	str	The SQL query or other operation to be executed.	required
parameters	Optional[Dict[str, Any]]	The parameters for the operation.	None
size	Optional[int]	The number of results to return; if None or 0, uses the value of fetch_size configured on the block.	None
**execution_options	Dict[str, Any]	Additional options to pass to connection.execute.	{}

Returns:

Type	Description
List[Row]	A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple.

Examples:

Execute operation with parameters, fetching two new rows at a time:

from prefect_gcp.bigquery import BigQueryWarehouse

with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
    operation = '''
        SELECT word, word_count
        FROM `bigquery-public-data.samples.shakespeare`
        WHERE corpus = %(corpus)s
        AND word_count >= %(min_word_count)s
        ORDER BY word_count DESC
        LIMIT 6;
    '''
    parameters = {
        "corpus": "romeoandjuliet",
        "min_word_count": 250,
    }
    for _ in range(0, 3):
        result = warehouse.fetch_many(
            operation,
            parameters=parameters,
            size=2
        )
        print(result)

Source code in prefect_gcp/bigquery.py

@sync_compatible
async def fetch_many(
    self,
    operation: str,
    parameters: Optional[Dict[str, Any]] = None,
    size: Optional[int] = None,
    **execution_options: Dict[str, Any],
) -> List["Row"]:
    """
    Fetch a limited number of results from the database.

    Repeated calls using the same inputs to *any* of the fetch methods of this
    block will skip executing the operation again, and instead,
    return the next set of results from the previous execution,
    until the reset_cursors method is called.

    Args:
        operation: The SQL query or other operation to be executed.
        parameters: The parameters for the operation.
        size: The number of results to return; if None or 0, uses the value of
            `fetch_size` configured on the block.
        **execution_options: Additional options to pass to `connection.execute`.

    Returns:
        A list of tuples containing the data returned by the database,
            where each row is a tuple and each column is a value in the tuple.

    Examples:
        Execute operation with parameters, fetching two new rows at a time:
        ```python
        from prefect_gcp.bigquery import BigQueryWarehouse

        with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
            operation = '''
                SELECT word, word_count
                FROM `bigquery-public-data.samples.shakespeare`
                WHERE corpus = %(corpus)s
                AND word_count >= %(min_word_count)s
                ORDER BY word_count DESC
                LIMIT 6;
            '''
            parameters = {
                "corpus": "romeoandjuliet",
                "min_word_count": 250,
            }
            for _ in range(0, 3):
                result = warehouse.fetch_many(
                    operation,
                    parameters=parameters,
                    size=2
                )
                print(result)
        ```
    """
    inputs = dict(
        operation=operation,
        parameters=parameters,
        **execution_options,
    )
    new, cursor = self._get_cursor(inputs)
    if new:
        await run_sync_in_worker_thread(cursor.execute, **inputs)

    size = size or self.fetch_size
    result = await run_sync_in_worker_thread(cursor.fetchmany, size=size)
    return result

fetch_one async

Fetch a single result from the database.

Repeated calls using the same inputs to any of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called.

Parameters:

Name	Type	Description	Default
operation	str	The SQL query or other operation to be executed.	required
parameters	Optional[Dict[str, Any]]	The parameters for the operation.	None
**execution_options	Dict[str, Any]	Additional options to pass to connection.execute.	{}

Returns:

Type	Description
Row	A tuple containing the data returned by the database, where each row is a tuple and each column is a value in the tuple.

Examples:

Execute operation with parameters, fetching one new row at a time:

from prefect_gcp.bigquery import BigQueryWarehouse

with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
    operation = '''
        SELECT word, word_count
        FROM `bigquery-public-data.samples.shakespeare`
        WHERE corpus = %(corpus)s
        AND word_count >= %(min_word_count)s
        ORDER BY word_count DESC
        LIMIT 3;
    '''
    parameters = {
        "corpus": "romeoandjuliet",
        "min_word_count": 250,
    }
    for _ in range(0, 3):
        result = warehouse.fetch_one(operation, parameters=parameters)
        print(result)

Source code in prefect_gcp/bigquery.py

@sync_compatible
async def fetch_one(
    self,
    operation: str,
    parameters: Optional[Dict[str, Any]] = None,
    **execution_options: Dict[str, Any],
) -> "Row":
    """
    Fetch a single result from the database.

    Repeated calls using the same inputs to *any* of the fetch methods of this
    block will skip executing the operation again, and instead,
    return the next set of results from the previous execution,
    until the reset_cursors method is called.

    Args:
        operation: The SQL query or other operation to be executed.
        parameters: The parameters for the operation.
        **execution_options: Additional options to pass to `connection.execute`.

    Returns:
        A tuple containing the data returned by the database,
            where each row is a tuple and each column is a value in the tuple.

    Examples:
        Execute operation with parameters, fetching one new row at a time:
        ```python
        from prefect_gcp.bigquery import BigQueryWarehouse

        with BigQueryWarehouse.load("BLOCK_NAME") as warehouse:
            operation = '''
                SELECT word, word_count
                FROM `bigquery-public-data.samples.shakespeare`
                WHERE corpus = %(corpus)s
                AND word_count >= %(min_word_count)s
                ORDER BY word_count DESC
                LIMIT 3;
            '''
            parameters = {
                "corpus": "romeoandjuliet",
                "min_word_count": 250,
            }
            for _ in range(0, 3):
                result = warehouse.fetch_one(operation, parameters=parameters)
                print(result)
        ```
    """
    inputs = dict(
        operation=operation,
        parameters=parameters,
        **execution_options,
    )
    new, cursor = self._get_cursor(inputs)
    if new:
        await run_sync_in_worker_thread(cursor.execute, **inputs)

    result = await run_sync_in_worker_thread(cursor.fetchone)
    return result

get_connection

Get the opened connection to BigQuery.

Source code in prefect_gcp/bigquery.py

def get_connection(self) -> "Connection":
    """
    Get the opened connection to BigQuery.
    """
    return self._connection

reset_cursors

Tries to close all opened cursors.

Source code in prefect_gcp/bigquery.py

def reset_cursors(self) -> None:
    """
    Tries to close all opened cursors.
    """
    input_hashes = tuple(self._unique_cursors.keys())
    for input_hash in input_hashes:
        cursor = self._unique_cursors.pop(input_hash)
        try:
            cursor.close()
        except Exception as exc:
            self.logger.warning(
                f"Failed to close cursor for input hash {input_hash!r}: {exc}"
            )

bigquery_create_table async

Creates table in BigQuery. Args: dataset: Name of a dataset in that the table will be created. table: Name of a table to create. schema: Schema to use when creating the table. gcp_credentials: Credentials to use for authentication with GCP. clustering_fields: List of fields to cluster the table by. time_partitioning: bigquery.TimePartitioning object specifying a partitioning of the newly created table project: Project to initialize the BigQuery Client with; if not provided, will default to the one inferred from your credentials. location: The location of the dataset that will be written to. external_config: The external data source. # noqa Returns: Table name. Example:

from prefect import flow
from prefect_gcp import GcpCredentials
from prefect_gcp.bigquery import bigquery_create_table
from google.cloud.bigquery import SchemaField
@flow
def example_bigquery_create_table_flow():
    gcp_credentials = GcpCredentials(project="project")
    schema = [
        SchemaField("number", field_type="INTEGER", mode="REQUIRED"),
        SchemaField("text", field_type="STRING", mode="REQUIRED"),
        SchemaField("bool", field_type="BOOLEAN")
    ]
    result = bigquery_create_table(
        dataset="dataset",
        table="test_table",
        schema=schema,
        gcp_credentials=gcp_credentials
    )
    return result
example_bigquery_create_table_flow()

Source code in prefect_gcp/bigquery.py

@task
async def bigquery_create_table(
    dataset: str,
    table: str,
    gcp_credentials: GcpCredentials,
    schema: Optional[List["SchemaField"]] = None,
    clustering_fields: List[str] = None,
    time_partitioning: "TimePartitioning" = None,
    project: Optional[str] = None,
    location: str = "US",
    external_config: Optional["ExternalConfig"] = None,
) -> str:
    """
    Creates table in BigQuery.
    Args:
        dataset: Name of a dataset in that the table will be created.
        table: Name of a table to create.
        schema: Schema to use when creating the table.
        gcp_credentials: Credentials to use for authentication with GCP.
        clustering_fields: List of fields to cluster the table by.
        time_partitioning: `bigquery.TimePartitioning` object specifying a partitioning
            of the newly created table
        project: Project to initialize the BigQuery Client with; if
            not provided, will default to the one inferred from your credentials.
        location: The location of the dataset that will be written to.
        external_config: The [external data source](https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/bigquery_table#nested_external_data_configuration).  # noqa
    Returns:
        Table name.
    Example:
        ```python
        from prefect import flow
        from prefect_gcp import GcpCredentials
        from prefect_gcp.bigquery import bigquery_create_table
        from google.cloud.bigquery import SchemaField
        @flow
        def example_bigquery_create_table_flow():
            gcp_credentials = GcpCredentials(project="project")
            schema = [
                SchemaField("number", field_type="INTEGER", mode="REQUIRED"),
                SchemaField("text", field_type="STRING", mode="REQUIRED"),
                SchemaField("bool", field_type="BOOLEAN")
            ]
            result = bigquery_create_table(
                dataset="dataset",
                table="test_table",
                schema=schema,
                gcp_credentials=gcp_credentials
            )
            return result
        example_bigquery_create_table_flow()
        ```
    """
    logger = get_run_logger()
    logger.info("Creating %s.%s", dataset, table)

    if not external_config and not schema:
        raise ValueError("Either a schema or an external config must be provided.")

    client = gcp_credentials.get_bigquery_client(project=project, location=location)
    try:
        partial_get_dataset = partial(client.get_dataset, dataset)
        dataset_ref = await to_thread.run_sync(partial_get_dataset)
    except NotFound:
        logger.debug("Dataset %s not found, creating", dataset)
        partial_create_dataset = partial(client.create_dataset, dataset)
        dataset_ref = await to_thread.run_sync(partial_create_dataset)

    table_ref = dataset_ref.table(table)
    try:
        partial_get_table = partial(client.get_table, table_ref)
        await to_thread.run_sync(partial_get_table)
        logger.info("%s.%s already exists", dataset, table)
    except NotFound:
        logger.debug("Table %s not found, creating", table)
        table_obj = Table(table_ref, schema=schema)

        # external data configuration
        if external_config:
            table_obj.external_data_configuration = external_config

        # cluster for optimal data sorting/access
        if clustering_fields:
            table_obj.clustering_fields = clustering_fields

        # partitioning
        if time_partitioning:
            table_obj.time_partitioning = time_partitioning

        partial_create_table = partial(client.create_table, table_obj)
        await to_thread.run_sync(partial_create_table)

    return table

bigquery_insert_stream async

Insert records in a Google BigQuery table via the streaming API.

Parameters:

Name	Type	Description	Default
dataset	str	Name of a dataset where the records will be written to.	required
table	str	Name of a table to write to.	required
records	List[dict]	The list of records to insert as rows into the BigQuery table; each item in the list should be a dictionary whose keys correspond to columns in the table.	required
gcp_credentials	GcpCredentials	Credentials to use for authentication with GCP.	required
project	Optional[str]	The project to initialize the BigQuery Client with; if not provided, will default to the one inferred from your credentials.	None
location	str	Location of the dataset that will be written to.	'US'

Returns:

Type	Description
List	List of inserted rows.

Example

from prefect import flow
from prefect_gcp import GcpCredentials
from prefect_gcp.bigquery import bigquery_insert_stream
from google.cloud.bigquery import SchemaField

@flow
def example_bigquery_insert_stream_flow():
    gcp_credentials = GcpCredentials(project="project")
    records = [
        {"number": 1, "text": "abc", "bool": True},
        {"number": 2, "text": "def", "bool": False},
    ]
    result = bigquery_insert_stream(
        dataset="integrations",
        table="test_table",
        records=records,
        gcp_credentials=gcp_credentials
    )
    return result

example_bigquery_insert_stream_flow()

Source code in prefect_gcp/bigquery.py

@task
async def bigquery_insert_stream(
    dataset: str,
    table: str,
    records: List[dict],
    gcp_credentials: GcpCredentials,
    project: Optional[str] = None,
    location: str = "US",
) -> List:
    """
    Insert records in a Google BigQuery table via the [streaming
    API](https://cloud.google.com/bigquery/streaming-data-into-bigquery).

    Args:
        dataset: Name of a dataset where the records will be written to.
        table: Name of a table to write to.
        records: The list of records to insert as rows into the BigQuery table;
            each item in the list should be a dictionary whose keys correspond to
            columns in the table.
        gcp_credentials: Credentials to use for authentication with GCP.
        project: The project to initialize the BigQuery Client with; if
            not provided, will default to the one inferred from your credentials.
        location: Location of the dataset that will be written to.

    Returns:
        List of inserted rows.

    Example:
        ```python
        from prefect import flow
        from prefect_gcp import GcpCredentials
        from prefect_gcp.bigquery import bigquery_insert_stream
        from google.cloud.bigquery import SchemaField

        @flow
        def example_bigquery_insert_stream_flow():
            gcp_credentials = GcpCredentials(project="project")
            records = [
                {"number": 1, "text": "abc", "bool": True},
                {"number": 2, "text": "def", "bool": False},
            ]
            result = bigquery_insert_stream(
                dataset="integrations",
                table="test_table",
                records=records,
                gcp_credentials=gcp_credentials
            )
            return result

        example_bigquery_insert_stream_flow()
        ```
    """
    logger = get_run_logger()
    logger.info("Inserting into %s.%s as a stream", dataset, table)

    client = gcp_credentials.get_bigquery_client(project=project, location=location)
    table_ref = client.dataset(dataset).table(table)
    partial_insert = partial(
        client.insert_rows_json, table=table_ref, json_rows=records
    )
    response = await to_thread.run_sync(partial_insert)

    errors = []
    output = []
    for row in response:
        output.append(row)
        if "errors" in row:
            errors.append(row["errors"])

    if errors:
        raise ValueError(errors)

    return output

bigquery_load_cloud_storage async

Run method for this Task. Invoked by calling this Task within a Flow context, after initialization. Args: uri: GCS path to load data from. dataset: The id of a destination dataset to write the records to. table: The name of a destination table to write the records to. gcp_credentials: Credentials to use for authentication with GCP. schema: The schema to use when creating the table. job_config: Dictionary of job configuration parameters; note that the parameters provided here must be pickleable (e.g., dataset references will be rejected). project: The project to initialize the BigQuery Client with; if not provided, will default to the one inferred from your credentials. location: Location of the dataset that will be written to.

Returns:

Type	Description
LoadJob	The response from load_table_from_uri.

Example

from prefect import flow
from prefect_gcp import GcpCredentials
from prefect_gcp.bigquery import bigquery_load_cloud_storage

@flow
def example_bigquery_load_cloud_storage_flow():
    gcp_credentials = GcpCredentials(project="project")
    result = bigquery_load_cloud_storage(
        dataset="dataset",
        table="test_table",
        uri="uri",
        gcp_credentials=gcp_credentials
    )
    return result

example_bigquery_load_cloud_storage_flow()

Source code in prefect_gcp/bigquery.py

@task
async def bigquery_load_cloud_storage(
    dataset: str,
    table: str,
    uri: str,
    gcp_credentials: GcpCredentials,
    schema: Optional[List["SchemaField"]] = None,
    job_config: Optional[dict] = None,
    project: Optional[str] = None,
    location: str = "US",
) -> "LoadJob":
    """
    Run method for this Task.  Invoked by _calling_ this
    Task within a Flow context, after initialization.
    Args:
        uri: GCS path to load data from.
        dataset: The id of a destination dataset to write the records to.
        table: The name of a destination table to write the records to.
        gcp_credentials: Credentials to use for authentication with GCP.
        schema: The schema to use when creating the table.
        job_config: Dictionary of job configuration parameters;
            note that the parameters provided here must be pickleable
            (e.g., dataset references will be rejected).
        project: The project to initialize the BigQuery Client with; if
            not provided, will default to the one inferred from your credentials.
        location: Location of the dataset that will be written to.

    Returns:
        The response from `load_table_from_uri`.

    Example:
        ```python
        from prefect import flow
        from prefect_gcp import GcpCredentials
        from prefect_gcp.bigquery import bigquery_load_cloud_storage

        @flow
        def example_bigquery_load_cloud_storage_flow():
            gcp_credentials = GcpCredentials(project="project")
            result = bigquery_load_cloud_storage(
                dataset="dataset",
                table="test_table",
                uri="uri",
                gcp_credentials=gcp_credentials
            )
            return result

        example_bigquery_load_cloud_storage_flow()
        ```
    """
    logger = get_run_logger()
    logger.info("Loading into %s.%s from cloud storage", dataset, table)

    client = gcp_credentials.get_bigquery_client(project=project, location=location)
    table_ref = client.dataset(dataset).table(table)

    job_config = job_config or {}
    if "autodetect" not in job_config:
        job_config["autodetect"] = True
    job_config = LoadJobConfig(**job_config)
    if schema:
        job_config.schema = schema

    result = None
    try:
        partial_load = partial(
            _result_sync,
            client.load_table_from_uri,
            uri,
            table_ref,
            job_config=job_config,
        )
        result = await to_thread.run_sync(partial_load)
    except Exception as exception:
        logger.exception(exception)
        if result is not None and result.errors is not None:
            for error in result.errors:
                logger.exception(error)
        raise

    if result is not None:
        # remove unpickleable attributes
        result._client = None
        result._completion_lock = None

    return result

bigquery_load_file async

Loads file into BigQuery.

Parameters:

Name	Type	Description	Default
dataset	str	ID of a destination dataset to write the records to; if not provided here, will default to the one provided at initialization.	required
table	str	Name of a destination table to write the records to; if not provided here, will default to the one provided at initialization.	required
path	Union[str, Path]	A string or path-like object of the file to be loaded.	required
gcp_credentials	GcpCredentials	Credentials to use for authentication with GCP.	required
schema	Optional[List[SchemaField]]	Schema to use when creating the table.	None
job_config	Optional[dict]	An optional dictionary of job configuration parameters; note that the parameters provided here must be pickleable (e.g., dataset references will be rejected).	None
rewind	bool	if True, seek to the beginning of the file handle before reading the file.	False
size	Optional[int]	Number of bytes to read from the file handle. If size is None or large, resumable upload will be used. Otherwise, multipart upload will be used.	None
project	Optional[str]	Project to initialize the BigQuery Client with; if not provided, will default to the one inferred from your credentials.	None
location	str	location of the dataset that will be written to.	'US'

Returns:

Type	Description
LoadJob	The response from load_table_from_file.

Example

from prefect import flow
from prefect_gcp import GcpCredentials
from prefect_gcp.bigquery import bigquery_load_file
from google.cloud.bigquery import SchemaField

@flow
def example_bigquery_load_file_flow():
    gcp_credentials = GcpCredentials(project="project")
    result = bigquery_load_file(
        dataset="dataset",
        table="test_table",
        path="path",
        gcp_credentials=gcp_credentials
    )
    return result

example_bigquery_load_file_flow()

Source code in prefect_gcp/bigquery.py

@task
async def bigquery_load_file(
    dataset: str,
    table: str,
    path: Union[str, Path],
    gcp_credentials: GcpCredentials,
    schema: Optional[List["SchemaField"]] = None,
    job_config: Optional[dict] = None,
    rewind: bool = False,
    size: Optional[int] = None,
    project: Optional[str] = None,
    location: str = "US",
) -> "LoadJob":
    """
    Loads file into BigQuery.

    Args:
        dataset: ID of a destination dataset to write the records to;
            if not provided here, will default to the one provided at initialization.
        table: Name of a destination table to write the records to;
            if not provided here, will default to the one provided at initialization.
        path: A string or path-like object of the file to be loaded.
        gcp_credentials: Credentials to use for authentication with GCP.
        schema: Schema to use when creating the table.
        job_config: An optional dictionary of job configuration parameters;
            note that the parameters provided here must be pickleable
            (e.g., dataset references will be rejected).
        rewind: if True, seek to the beginning of the file handle
            before reading the file.
        size: Number of bytes to read from the file handle. If size is None or large,
            resumable upload will be used. Otherwise, multipart upload will be used.
        project: Project to initialize the BigQuery Client with; if
            not provided, will default to the one inferred from your credentials.
        location: location of the dataset that will be written to.

    Returns:
        The response from `load_table_from_file`.

    Example:
        ```python
        from prefect import flow
        from prefect_gcp import GcpCredentials
        from prefect_gcp.bigquery import bigquery_load_file
        from google.cloud.bigquery import SchemaField

        @flow
        def example_bigquery_load_file_flow():
            gcp_credentials = GcpCredentials(project="project")
            result = bigquery_load_file(
                dataset="dataset",
                table="test_table",
                path="path",
                gcp_credentials=gcp_credentials
            )
            return result

        example_bigquery_load_file_flow()
        ```
    """
    logger = get_run_logger()
    logger.info("Loading into %s.%s from file", dataset, table)

    if not os.path.exists(path):
        raise ValueError(f"{path} does not exist")
    elif not os.path.isfile(path):
        raise ValueError(f"{path} is not a file")

    client = gcp_credentials.get_bigquery_client(project=project)
    table_ref = client.dataset(dataset).table(table)

    job_config = job_config or {}
    if "autodetect" not in job_config:
        job_config["autodetect"] = True
        # TODO: test if autodetect is needed when schema is passed
    job_config = LoadJobConfig(**job_config)
    if schema:
        # TODO: test if schema can be passed directly in job_config
        job_config.schema = schema

    try:
        with open(path, "rb") as file_obj:
            partial_load = partial(
                _result_sync,
                client.load_table_from_file,
                file_obj,
                table_ref,
                rewind=rewind,
                size=size,
                location=location,
                job_config=job_config,
            )
            result = await to_thread.run_sync(partial_load)
    except IOError:
        logger.exception(f"Could not open and read from {path}")
        raise

    if result is not None:
        # remove unpickleable attributes
        result._client = None
        result._completion_lock = None

    return result

bigquery_query async

Runs a BigQuery query.

Parameters:

Name	Type	Description	Default
query	str	String of the query to execute.	required
gcp_credentials	GcpCredentials	Credentials to use for authentication with GCP.	required
query_params	Optional[List[tuple]]	List of 3-tuples specifying BigQuery query parameters; currently only scalar query parameters are supported. See the Google documentation for more details on how both the query and the query parameters should be formatted.	None
dry_run_max_bytes	Optional[int]	If provided, the maximum number of bytes the query is allowed to process; this will be determined by executing a dry run and raising a ValueError if the maximum is exceeded.	None
dataset	Optional[str]	Name of a destination dataset to write the query results to, if you don't want them returned; if provided, table must also be provided.	None
table	Optional[str]	Name of a destination table to write the query results to, if you don't want them returned; if provided, dataset must also be provided.	None
to_dataframe	bool	If provided, returns the results of the query as a pandas dataframe instead of a list of bigquery.table.Row objects.	False
job_config	Optional[dict]	Dictionary of job configuration parameters; note that the parameters provided here must be pickleable (e.g., dataset references will be rejected).	None
project	Optional[str]	The project to initialize the BigQuery Client with; if not provided, will default to the one inferred from your credentials.	None
result_transformer	Optional[Callable[[List[Row]], Any]]	Function that can be passed to transform the result of a query before returning. The function will be passed the list of rows returned by BigQuery for the given query.	None
location	str	Location of the dataset that will be queried.	'US'

Returns:

Type	Description
Any	A list of rows, or pandas DataFrame if to_dataframe,
Any	matching the query criteria.

Example

Queries the public names database, returning 10 results.

from prefect import flow
from prefect_gcp import GcpCredentials
from prefect_gcp.bigquery import bigquery_query

@flow
def example_bigquery_query_flow():
    gcp_credentials = GcpCredentials(
        service_account_file="/path/to/service/account/keyfile.json",
        project="project"
    )
    query = '''
        SELECT word, word_count
        FROM `bigquery-public-data.samples.shakespeare`
        WHERE corpus = @corpus
        AND word_count >= @min_word_count
        ORDER BY word_count DESC;
    '''
    query_params = [
        ("corpus", "STRING", "romeoandjuliet"),
        ("min_word_count", "INT64", 250)
    ]
    result = bigquery_query(
        query, gcp_credentials, query_params=query_params
    )
    return result

example_bigquery_query_flow()

Source code in prefect_gcp/bigquery.py

@task
async def bigquery_query(
    query: str,
    gcp_credentials: GcpCredentials,
    query_params: Optional[List[tuple]] = None,  # 3-tuples
    dry_run_max_bytes: Optional[int] = None,
    dataset: Optional[str] = None,
    table: Optional[str] = None,
    to_dataframe: bool = False,
    job_config: Optional[dict] = None,
    project: Optional[str] = None,
    result_transformer: Optional[Callable[[List["Row"]], Any]] = None,
    location: str = "US",
) -> Any:
    """
    Runs a BigQuery query.

    Args:
        query: String of the query to execute.
        gcp_credentials: Credentials to use for authentication with GCP.
        query_params: List of 3-tuples specifying BigQuery query parameters; currently
            only scalar query parameters are supported.  See the
            [Google documentation](https://cloud.google.com/bigquery/docs/parameterized-queries#bigquery-query-params-python)
            for more details on how both the query and the query parameters should be formatted.
        dry_run_max_bytes: If provided, the maximum number of bytes the query
            is allowed to process; this will be determined by executing a dry run
            and raising a `ValueError` if the maximum is exceeded.
        dataset: Name of a destination dataset to write the query results to,
            if you don't want them returned; if provided, `table` must also be provided.
        table: Name of a destination table to write the query results to,
            if you don't want them returned; if provided, `dataset` must also be provided.
        to_dataframe: If provided, returns the results of the query as a pandas
            dataframe instead of a list of `bigquery.table.Row` objects.
        job_config: Dictionary of job configuration parameters;
            note that the parameters provided here must be pickleable
            (e.g., dataset references will be rejected).
        project: The project to initialize the BigQuery Client with; if not
            provided, will default to the one inferred from your credentials.
        result_transformer: Function that can be passed to transform the result of a query before returning. The function will be passed the list of rows returned by BigQuery for the given query.
        location: Location of the dataset that will be queried.

    Returns:
        A list of rows, or pandas DataFrame if to_dataframe,
        matching the query criteria.

    Example:
        Queries the public names database, returning 10 results.
        ```python
        from prefect import flow
        from prefect_gcp import GcpCredentials
        from prefect_gcp.bigquery import bigquery_query

        @flow
        def example_bigquery_query_flow():
            gcp_credentials = GcpCredentials(
                service_account_file="/path/to/service/account/keyfile.json",
                project="project"
            )
            query = '''
                SELECT word, word_count
                FROM `bigquery-public-data.samples.shakespeare`
                WHERE corpus = @corpus
                AND word_count >= @min_word_count
                ORDER BY word_count DESC;
            '''
            query_params = [
                ("corpus", "STRING", "romeoandjuliet"),
                ("min_word_count", "INT64", 250)
            ]
            result = bigquery_query(
                query, gcp_credentials, query_params=query_params
            )
            return result

        example_bigquery_query_flow()
        ```
    """  # noqa
    logger = get_run_logger()
    logger.info("Running BigQuery query")

    client = gcp_credentials.get_bigquery_client(project=project, location=location)

    # setup job config
    job_config = QueryJobConfig(**job_config or {})
    if query_params is not None:
        job_config.query_parameters = [ScalarQueryParameter(*qp) for qp in query_params]

    # perform dry_run if requested
    if dry_run_max_bytes is not None:
        saved_info = dict(
            dry_run=job_config.dry_run, use_query_cache=job_config.use_query_cache
        )
        job_config.dry_run = True
        job_config.use_query_cache = False
        partial_query = partial(client.query, query, job_config=job_config)
        response = await to_thread.run_sync(partial_query)
        total_bytes_processed = response.total_bytes_processed
        if total_bytes_processed > dry_run_max_bytes:
            raise RuntimeError(
                f"Query will process {total_bytes_processed} bytes which is above "
                f"the set maximum of {dry_run_max_bytes} for this task."
            )
        job_config.dry_run = saved_info["dry_run"]
        job_config.use_query_cache = saved_info["use_query_cache"]

    # if writing to a destination table
    if dataset is not None:
        table_ref = client.dataset(dataset).table(table)
        job_config.destination = table_ref

    partial_query = partial(
        _result_sync,
        client.query,
        query,
        job_config=job_config,
    )
    result = await to_thread.run_sync(partial_query)

    if to_dataframe:
        return result.to_dataframe()
    else:
        if result_transformer:
            return result_transformer(result)
        else:
            return list(result)